Tory leadership betting: RED Davis, BLACK Clarke, BLUE Cameron, GREEN Fox

But what if the rule changes are rejected?

With the Labour Conference, the Scottish by-elections and the announcement on Tuesday of whether the Howard changes to the Tory leadership rules have gone through it’s the biggest week in British politics since the General Election in May.

For the Tory leadership our latest chart shows further a improvements in the implied probability of David Davis winning based on the latest best betting prices.

It certainly looks as though the momentum is with the Shadow Home Secretary and the view of the other contenders, as the Observer reports this morning, is that Davis will benefit most if Tuesday’s decision on how the leader is chosen puts the final say in the hands of MPs. This is a complete reversal of the view at the start of this contest when it was thought that Davis would fare better if it went out to the membership at large.

We had thought that the move to Davis in the past few days was based on leaks about how the rule change ballot was going. However the amount of money that’s been required to shift his price has been very small – just £8,000, for instance, in a week has been traded on him on Betfair.

The big factor will be what happens in Blackpool next week. What will be mood of the party as one candidate after another set out their stalls to delegates? Opinion polls could also be crucial in shaping views particularly if there are more surveys showing Clarke convincingly ahead in both the country and amongst Tories.

Blackpool also gives a chance to the other contenders – Liam Fox, Sir Malcolm Rifkind and David Cameron – to put some traction into their campaigns. They must be hoping to make a speech that resonates with the party because this could possibly make a difference.

Davis’s big challenge is that he is still relatively unknown amongst the general public and the last time the party chose someone like that they ended up with Ian Duncan Smith.

Davis’s strong point is the support he has managed to garner amongst the party’s MPs – though whether they will do in private what they say in public is a different matter. This could be crucial if the rules remain unchanged because then the parliamentary party ballot to select which two contenders go on to the final ballot of members. Anti-Clarke factions could work to block him out of this even if the polls continue to show that he is the first choice amongst the membership.

It is hard to call against Davis but he still has a lot of work to do.

Tory leadership betting prices

Conventional bookmakers best price: Davis 8/15: Clarke 9/4: Cameron 13/2: Fox 16/1: Rifkind 25/1

Betfair betting exchange: Davis 0.47/1: Clark 4/1: Cameron 12.5/1: Fox 14.5/1: Rifkind 47/1

BinaryBet spread market. Davis 59-66: Clarke 19-25: Cameron 6-10 Fox 5-8: Rifkind 1-3

Mike Smithson